Flexible hose or conduit is used in a variety of applications. These applications may include the transportation of fluids such as liquids and gases from one location to another. In heating, ventilation and air conditioning (HVAC) systems for example, flexible hose or ducting may be used to transport cooled or heated air for ventilation purposes from one location to another. Flexible hose may also be used to remove exhaust from a location. Another application for flexible hose or conduit is in the area of vacuum systems that are used for the removal of debris or particulate matter from an area. Flexible hose is typically comprised of a body which is usually generally circular in cross section and provided with at least one connection means at one end of the hose for connecting the flexible hose to an apparatus for moving the transported medium through the hose. The other end of the flexible hose can have any one of a number of attachments present. In the area of flexible hose for vacuum cleaners for example, the attachments may include an assortment of brushes that may connect directly to the end of the hose or to one or more wands.
Preferably, the hose is made of a material that is impermeable to fluids to prevent leakage and also resistant to punctures and tears. Flexible hose is typically made of a thermoplastic material that provides flexibility and some measure of strength. As the thermoplastic material is made thinner to provide greater flexibility there is increased risk of tears and punctures due to the thin sidewall of the hose. If the thermoplastic material is made thicker to reduce the risk of tears and punctures there is a tendency for the hose to lose the necessary flexibility. Flexibility is important in many applications because the hose is bent during use or must bend around obstacles as it is used. Flexibility is also important in many applications where the hose is compressed or stretched by the user to fit a piece of hose to a given area or location. Strength is important not only in the area of punctures and tears but also in connection with crushing or kinks. Hose that is exposed and not buried in the wall or a ceiling of a building may be subjected to crushing forces due to dropped objects, stepping on the hose, etc. In addition, as the hose is bent, the hose needs to retain its inner diameter as much as possible to prevent the hose from blocking circulation. As a result, the hose must exhibit sufficient strength or flexibility to prevent crushing when a load is placed on the hose and/or the ability to revert to generally its initial configuration when a load is removed from the hose.
In many instances, the thermoplastic material that is the outer covering of the hose is reinforced by a helical member that is imbedded in or adhered to the inner or interior wall of the thermoplastic material. The helical member may be a metallic or non-metallic material. This helix is adhered to the inner surface of the thermoplastic covering usually during the extrusion process or by means of a suitable solvent that bonds the helix to the thermoplastic outer wall of the hose. A metal helix is usually covered with a plastic material or cloth so that the surface of the metal is not in contact with the interior of the hose. The helix provides strength to the hose and helps prevent the hose from being crushed. The helix also provides additional flexibility to the hose from the standpoint of permitting it to be stretched slightly.
In the area of vacuum hose i.e., hose that is used in applications where the hose is used to remove particulate matter from a material, there are a number of types of vacuum systems currently available on the market. Many commercially available vacuum cleaning systems today are relatively portable and have a housing that includes a filter chamber, a vacuum motor located in the vicinity of one end of the filter chamber and a hose connected to the filter chamber. The motor provides the suction force for removing the particulate matter. The housing may for example be in the form of a portable “canister.” The vacuum chamber may for example house a receptacle or bag for containing the particulate matter picked up through the hose by the motor. The vacuum system may also be an “upright” vacuum. Although a use is not always used in an upright vacuum, there are many models currently available where a hose and various attachments may be connected to the upright vacuum to increase its versatility. The vacuum system may also be part of a central vacuum system in a building where there is one or more stationery motors located in the building in a fixed position and there are a plurality of hoses or ducts within the walls of the building which extend from the motor to each room in the structure. These internal hoses have a connection means at the wall surface whereby a flexible hose may be attached so that the room may be vacuumed. In this system the user does not have to carry a heavy canister throughout the premises.
One type of vacuum hose that is currently available is a current carrying hose which has embedded in the hose the necessary wiring to carry current from one end of the hose to the other. This is useful in many vacuum cleaner applications where for example a light bulb or cleaning tool such as rotating brushes are present at the end of a hose or wand that is connected to the hose. In order for the light or brushes to work there must be a means for extending current from the housing to the fixture. Heretofore, current carrying hose was rather rigid and was incapable of stretching to extend its length a significant distance.
Another type of hose that is presently available is known as a stretch hose. While most flexible hose has some ability to stretch a short distance stretch hose typically can stretch a distance 2 to 6 times its at rest length. The benefit of a stretch hose is that as the user is working a manageable length of hose is carried. For example, when vacuuming a floor the canister need not constantly roll behind the user because the hose can stretch to cover a greater area without having to move the canister. In addition, for both upright, canister and built-in systems the stretch hose is useful on stairs or to reach the tops of cabinets, drapes and other high areas where an ordinary hose cannot reach without additional wands or extensions. Once the extra length of hose is no longer needed the stretched hose retracts to its normal, more compact configuration.